Nongalling plug valve



July1.6,194o. QRSCHERE'R" .12,208,394

l NoN-GALLING PLUG VALVE INV ENTOR.

ATTORNEY.

Patented July 1e, 1940 2,208,394-

UNITED STATES PATENT. OFFICE 2,208,394 NONGALLI'NG PLUG VALVE George F. Scherer, San Francisco, Calif., assignor to Merco Nordstrom Valve Company. Pittsburgh, Pa., a corporation of Delaware Application August 26, 1938, Serial No. 226,961 3 claims. (ci. 251-4101) In the manufacture of steel plug valves it hereabout 45 to 52%, cobalt, 28 to 32% chromium, tofore has been proposed to overcome the char- 10 to 15% tungsten and about 2.5% carbon. The acteristic property of the steel plug -and seat to alloy coating 5 preferably is built up on the valve seize or gall by employing a vhardened steel plug. plug surface, which previously has been heated and a soft steel seat, for example, the plug being to a suitable temperature, by any suitable fusion 5 hardened by quenching or being case hardened welding method. The alloy flows readily when by carburizing or nitriding. However, such melted and is evenly distributed over the plug valves are not satisfactory for services where surfaces and forms an excellent bond therewith. they are subject to temperatures at which the The coated plug is then slowly cooled in a furhardness is decreased or lost, as the valve therenace to prevent cracks and to maintain a perl0 upon reverts to its tendency to gall. This galling fect bond. The thickness of the coating may characteristic is also accentuated at elevated range from a few thousandths of an inch up to temperatures in lubricated plug cocks by even any desired thickness. Preferably the alloy a slight loss in hardness because at such temcoating employed is about si; of an inch thick beperatures the reduced viscosity of the lubricant fore grinding. The plug is then ground to the 1l may permit intimate metal to metal contact of proper-final dimension, then lapped into its seat the plug and seat. at normal or elevated temperatures. The bond According to the present invention, the gallobtained in this manner between the alloy and ing in plug valves is overcome by coating the the plug is excellent and there is no spalling seating surfaces of the steel plug or seat, or both, olf of the alloy surface. The alloy coating proso with a hard, nongalling metal which retains its vides nongalling characteristics at both normal nongalling properties at elevated temperatures and elevated temperatures, along with corrosion and which preferably is corrosion resistant. T'he resistance of the same order as the KA-Z-S various non-ferrous cobalt-chromium-tungsten variety of stainless steel and excellent erosion welding allows are especially valuable for this resisting properties. Any suitable lubricating 25 purpose, as they are extremely hard, maintain system may be employed for lubricating the seat their hardness practically unimpaired up to about 3 of the valve, the system illustrated comprising 1000 F., and with slight impairment at tema. reservoir 6 in the stem having radial ducts 'l peratures up to 1500 F. or higher, and are excommunicating with longitudinal grooves 8 in the tremely resistant to corrosion, being in the same plug surface. The grooves may be ground into 30 general corrosion resisting range as the the alloy coating, or may be previously formed chromium nickel stainless steels. They possess in the plug deep enough to receive an alloy distinct nongalling characteristics either in concoating.

tact with a surface of the same composition or In the modication shown in Figure 2 the alloy any of the several cobalt-chromium-tungsten coat l1 is welded to the plug surface, and an alloy 35 alloy variants or `in contact with ordinary carcoating 5 is welded on the surface 3 of the casing.

bon steel or chromium nickel steel, probably due The alloy surfaces then are ground and the plug to their exceedingly low co-eillcient of friction, is lapped into its seat.

which is lower than other metals. The most common cobalt-chromium-tungsten The invention will be described in connection alloys are the following: 40

with the accompanying drawing wherein I have l shown by way of example preferred embodiments Pecnt Pecnt regent Percent C Ni Mo of my invention, and wherein:

Figure 1 is a sectional view of a plug valve having a coating of hard nongalling metal on the :ggg gj g n 45 plus', 6.3-68 2T-ao l as Figure 2 shows a modified construction having E g2g ggg?, lgig 5,0275 a coating of hard nongalling metal on the plug 38 ao 16 a5 1o 4 and seat, and

Figure 3 shows a further modification having a The alloy coatings may be welded to steel or 60 coating on the plug and seat. iron sleeves which are then keyed to either or Referring to the drawing, Figure 1, there is both the plug and body. 'I-'hisis desirable mainly shown a body l made of ordinary cast carbon for the larger sizes of valves in order to secure steel. A plug 4 is located in the seat 3 and has more uniform expansion and contraction strains a coating 5 on its surface of an alloy containing in the metal base to which the welded coating is 55 applied. A further advantage of this constructionis that when the alloy coating becomes worn the sleeve may be removed and a new coated sleeve then inserted.

In the modication shown in Figure 3, the valve plug I3, which may be of carbon steel, is coated with a coating I4 of an alloy containing 45 to 52% cobalt, 28 to 32% chromium, l0 to 15% tungsten, and about 2.5% carbon, and the casing I5, vihich is of ordinary carbon steel, has atapered sleeve I1 of carbon steel secured therein in any suitable manner and having a coating I6 of an alloy containing .about 52 to 58% cobalt, 30 to 34% chromium, and 6 to 10% tungsten. In this modication an alloy coating I8 preferably is formed around the plug port I9 and'a coating 2| preferably is formed around the valve passage in order to provide protection against corrosion 'and erosion.

In plug valves, wherein the plug surface slides over the seat surface, the maintenance of proper seating surfacesis of the utmost importance and valves constructed in accordance with the present invention provide co-operating seating surfaces which arev highly resistant to corrosion and erosion. The nongalling characteristics remain unimpaired under a wide range of conditions inciuding erosive and corrosive conditions and operation at elevated temperatures or lnormal temperatures. Although the galling tendency exhibited by steel valves is not present in uncoated cast v iron valves, this alloy coating can also be applied to iron valves for increasing the corrosion resistance and erosion resistance of such valves.

The invention may also be applied to the type of plug valve shown in the application for Letters Patent of Sven J. Nordstrom, Serial No. 691,213,` iiled September 27, 1933', for Valve, and now Patent No. 2,177,873 issued October 31, '1939.

The present invention contemplates applying the alloy coatings to plug valves of other metals for high temperature services, such as stainless steels or other alloy steels which form a good bond thereto.

What I claim 'as my invention and desire to secure by Letters Patent is:

1. A plug valve comprising a steel body having a seat therein, a steel plug in said seat in sliding contact therewith and having a coating on at least one of the seating surfaces of the valve of a hard nongalling. cobalt-chromium-tungsten alloy which retains its non-galling property at temperatures at or above about 500 F.

2. A plug valve comprising a steel casing having a seat therein coated with a hard nongalling cobalt-chromium-tungsten alloy, and asteel plug in said seat in sliding contact therewith having a coating of vhard nongalling cobalt-chromiumtungsten alloy on its seating surface.

y 3. A plug valve'comprising a body of chromium nickel steel having a seat therein and a plug-of chromium nickel steel in sliding contact therewith, at least one of the seating surfaces of the V valve being coated with a hard nongalling'cobaltchromium-tungsten alloy.

GEORGE F. SCHERER.

CERTIFICATE OE CORRECTION. Patent lio-. 2,208,59L. July 16. 191;,0.

GEORGE F. scEERER.

It is h ereay' certified that error appears in the printed specification of the above numbered patent requirig correction as follows: Page 1, seci ond column, lihe lg? ,in the table fourth column thereof, for "6.10I read 6-10 ondthat the said Letters Patent shouldbe read with this correction therein that the same may conform/to the record of the case in-the Potent Office.

signed and sealed this 11th any of February, A. D.' 19in.

A Aredale, (S'el) y Acting Commissioner of Patents.- 

